Radio noise when using dc power supply

[ronniewarren]

I just purchased a 1992 sunline truck camper. Has dc power supply that automatically powers camper when plugged in. AM/FM radio in camper works great when working of truck battery alone. However when operating from dc power supply the noise and harsh hum is so bad in radio it will not work. There is a little black box wird in behind radio that when moved around agitates problem even more. Any advice on how to solve my problem.

[OhhWell]

Any idea what the little black box does? Is it wired to the incoming power supply? My first thought is that your power converter is sending out dirty power to the 12v but having the odd black box influence the noise is interesting.

Unfortunately, we recently got rid of our 94 or I would look behind the radio to compare.

I know in car audio that was usually an indication of something being grounded improper.

[mainah]

It sure sounds as if you have a converter issue. If you have a volt meter check you DC power with the meter on the AC setting if it reads AC voltage your converter is giving you problems every thing most likely is working fine they will tolerate AC voltage.

[OPIE]

I had the same problem with my trailer. I wasn't paying for a new converter, and the filter was useless, way too may ground issues in a old trailer. Finally I gave up and wired a switch and a seperate circuit to the battery directly. No issues now, as long as remember to turn the switch off so the radio light doesn't drain the battery.